Hydraulic pump or motor apparatus



June 9, 1964 Filed Nov. 2, 1961 J. T. TIMMS HYDRAULIC PUMP OR MOTORAPPARATUS 2 Sheets-Sheet 1 June 9, 1964 J. T. TlMMS HYDRAULIC PUMP ORMOTOR APPARATUS 2 Sheets-Sheet 2 Filed NOV. 2, 1961 United States PatentHYDRAULIC PUMP 0R MOTOR APPARATUS Jack T. Timms, Newcastle-upon-Tyne,England, assignor to George Angus 8; Company Limited, Newcastle-upon-Tyne, England Filed Nov. 2, 1961, Ser. No. 149,632 Claims priority,application Great Britain Nov. 9, 1960 4 Claims. (Cl. 103161) Thisinvention relates to hydraulic pump or motor apparatus of the kind inwhich substantially the same apparatus will pump if driven mechanicallyor act as a motor if supplied with liquid under pressure.

The invention is applied to such apparatus in which a rotary cylinderbarrel, such as a multiple radial-cylinder barrel, has axially-directedliquid-transfer ports with which co-operates a non-rotary face valvewhich is thrust axially against a port face of the cylinder barrel.

The hydraulic liquid has access between the opposed faces of thecylinder barrel and valve, thus lubricating these faces for the cylinderbarrel to rotate, but the liquid which passes between these facesescapes from the hydraulic circuit and shows a loss in the hydraulic efficiency of the apparatus. The clearance between the cylinder barrel andvalve faces must therefore be kept as small as possible and the liquidin this small clearance is at high pressure, with a reducing gradient inthe direction of escape, usually radially inward and outward. The liquidin the clearance consequently exerts an axial separating thrust which isnot uniform across the clearance and this separating thrust must beopposed by axial balancing thrust on the valve sufficient to limit theclearance and applied so as not to distort the valve when high pressuresare used, e.g. 2000 p.s.i. and upwards.

It has previously been proposed to effect the axial balancing thrust onthe valve by hollow pistons and hollow piston rods, thrustingmechanically on the valve, the pistons and rods forming part of thehydraulic circuit through which liquid is led to and from the valve andthe liquid acting on the hollow pistons to produce the required axialbalancing thrust.

An object of the present invention is to provide an improved way ofutilising the pressure of the hydraulic liquid to achieve the requiredaxial balanced thrust on the valve.

For the above purpose, in hydraulic pump or motor apparatus having arotary cylinder barrel with an axiallydirected face through whichliquid-transfer ports open against an opposed face of a non-rotatingface valve thrust axially against the barrel face and having at leastone passageway to lead liquid under pressure to or from the ports, therebeing a leakage path for the liquid under pressure between the opposedfaces of the barrel and valve, according to the invention eachpassageway in the valve has a wall surface directed substantiallyaxially away from the barrel face, the axial projected area of thepassageway wall surface is such that the resultant effect of liquidunder pressure in the passageway has an axial component thrusting thevalve against the barrel face and the shape and location of theaxially-directed wall surface in each passageway are such that theconsequent axial thrust on the valve is symmetrically distributed withrespect to the opposing axial thrust of liquid between the opposed facesof the barrel and valve.

In a preferred embodiment, in a reversible pump or motor apparatus, thevalve has two similar passageways, both capable of serving for eitherdirection of liquid flow, and the two passageways are arrangedsymmetrically on opposite sides of the rotary axis.

An effective shape for the axially-directed wall surface of eachpassageway is an arcuate shape, such as a kidney,

3,136,263 Patented June 9, 1964 "ice sickle or circular segment,subtending at the rotary axis an angle as near as possible to 180. Thesubtended angle in a valve with two passageways is limited to less than180 by the need to keep the two passageways separate and leave enoughmaterial between their ends for the valve to have a strong structure.

The valve must be connected for liquid flow through the pump casing, orequivalent fixed part, at the opposite side from the cylinder barrel andeach valve passageway therefore has a corresponding casing passageway towhich it is connected by a joint which is liquid-tight but permits thesmall axial movement of the valve necessary to permit the valve to bethrust against the cylinder barrel. The valve is also held againstrotation, such as by axial dowels between the valve and casing allowingsmall axial movement of the valve.

Each joint between the valve and easing passageways can be sealed by aliner or internal sleeve, telescoping into enlargements of the twoopposed passageway-ends so that the bore of the liner conforms locallyto the bore of the passageways.

In the preferred form of the invention, each valve passageway, at theend remote from the valve face, has a mouth which is of arcuate shape,is opposed to a casing passageway end of the same shape and is joinedthereto by a tubular liner of corresponding arcuate cross-sectionalshape.

An arcuate tubular liner, such as of kidney shape, can be made from acircular tubular blank of resiliently deformable material, such asnylon, which is thermo-plastic at a temperature higher than the maximumworking temperature which the liner is intended to encounter, the blankbeing placed in the working position of the liner, or in a formerproviding the same shape as is required in the working position, andbeing moulded to shape under internal fluid pressure at a temperature atwhich I some parts being omitted to facilitate illustration.

The pump as shown by the drawings operates on a well-known principle asregards its pumping action but includes new features of constructionincluded within the present invention.

The pump has a casing, made in two main parts 1 and 2, in which amultiple, inclined radial, cylinder barrel 3, with pistons 4, is mountedon a shaft 5 by radial bearings 6 and 7 and an axial thrust bearing 8.

The pistons 4 bear, by their outer spherically-shaped heads, against theinner cylindrical surface of the inner race 9 of a large diameter rollerbearing, surrounding the cylinder barrel 3, and of which the outer race10 is held against rotation by a frame 11 in the casing part 1. Thebearing race 10 either has a constant eccentricity to the cylinderbarrel axis or the frame 11 is mounted for such eccentricity to bevariable. When the cylinder barrel 3 is rotated, by a drive applied tothe shaft 5, the pistons 4 tend to move outward in their cylinders,under centrifugal force, and to the extent to which the surroundingroller bearing 9, 10 is eccentric, the pistons are successively thrustinwards as they sweep the closer arc of the race 9. As the pistons moveoutwards, sweeping the further arc of the race 9, they each make asuction stroke in their respective cylinders, drawing liquid through aport 12 in each respective cylinder, and as they are thrust inwards theyeach discharge liquid through the same port 12. The bearing 9, thusprovides, in a simple and robust construction, a reaction ring as knownin apparatus of this kind.

The ports 12 emerge at a transverse face 13 of the cylinder barrel 3 inaxial opposition, with a small working clearance, to the transverse face14 of a valve 15 held against rotation, with a small freedom for axialmovement, by dowels in holes 16 in the valve 15 (see FIG. 2) and opposedholes in the casing part a. The valve 15 has two passageways 17 and 18,one for suction and the other for delivery of liquid according to thedirection of eccentricity of the reaction ring (the bearing 9, 10), andthe casing part 2 has two corresponding passageways 19 and 20. The twopairs of passageways 1'7, 19 and 18, 20 are each joined by a liner 21,sealed by O-rings 22, and the opposed mouths of the passageways and theliners all have the same arcuate cross-sectional shape as can be seen inFIG. 2. The liners 21 are of nylon and are made as described above.

Within each valve passageway 17 and 18 an inclined transverse part 1'7or 18 of the Wall surface is directed substantially axially away fromthe cylinder barrel face 13 and the area of each such surface part iscalculated so that the effect of the pressure of liquid in therespective passageway has an axial component sufficient to balance theseparating effect of the pressure of liquid between the faces 13 and 14.

The shape and location of each passageway wall surface part 17 and 18also is calculated such that the liquid pressure thereon is distributedappropriately with regard tothe distribution of pressure between thefaces 13 and 14 and the valve 15 is not subjected to undueasymmetrically opposed pressure forces which would cause distortion ofthe valve or spoil the uniformity of clearance between the faces 13 and14.

In designing a valve for any particular apparatus, it

. 4 which the fluid pressure will produce a balancing force preventingmore than the desired minimum separation of the valve and cylinderbarrel faces without causing the valve to tilt or distort under theopposing forces to which it is subjected.

I claim:

1. In hydraulic apparatus operable as a pump or a motor and having acasing, a rotary cylinder barrel in said casing, and axially directedface of said barrel having liquid-transfer ports, a non-rotating facevalve opposed axially against said barrel face, said casing and saidvalve each having therethrough two passageways arranged symmetrically onopposite sides of the rotary axis of said barrel and in operativecommunication with said ports, the improvement comprising mutuallyopposed ends of said passageways in said casing and said valve being ofthe same arcuate cross-sectional shape subtending an angle of nearly 180to said axis and said passageways in said valve each having a wallsurface directed substantially axially away from said barrel face andbeing of arcuate shape subtending an angle of nearly 180 to said axis.

2. In hydraulic apparatus as claimed by claim 1, a liner in each twomutually opposed ends of said passageways in telescopic interconnectiontherewith and of the same cross-sectional shape as said ends of saidpassageways.

3. In hydraulic apparatus as claimed by claim 2, said liner and saidmutuallyopposed ends of said passageis necessary to determine the arearequired for the valve ports and the area available for the sealing faceof the valve against the cylinder barrel. The value, as a func tion ofthe working pressure, and the line of action of the axial force tendingto separate the opposed valve and cylinder barrel faces can then becalculated on the basis of the pressure distribution acrossthese facesdue to the liquid leaking between and lubricating them.

To oppose the axial separating force, it is necessary to apply to thevalve a coaxial balancing force of slightly greater value and the area,-shape and position of the valve passageway wall surfaces required forthe fluid pressure to produce the balancing force can be calculated.

On the above basis it is possible to design a valve withaxially-directed Wall surfaces of arcuate shape on ways being ofcircular segmental cross-sectional shape centered on said rotary axis.

4. In hydraulic apparatus as claimed by claim 1, said mutually opposedends of said. passageways being of circular segmental cross-sectionalshape centered on said rotary axis.

References (Iited in the file of this patent UNITED STATES PATENTS2,033,464 Ferris Mar. 10, 1936 2,069,651 Ferris Feb. 2, 1937 2,397,314Grosser Mar. 26, 1946 2,525,498 Naylor et al Oct. 10, 1950 2,608,933Ferris Sept. 2, 1952 2,932,256 Orshansky Apr. 12, 1960 2,977,891 BishopApr. 4, 1961 3,010,405 Tomell Nov. 28, 1961 3,028,814 'Rumsey et al.Apr. 10, 1962 FOREIGN PATENTS 470,950 France Oct. 6, 1914 111,692 GreatBritain Nov. 15, 1917

1. IN HYDRAULIC APPARATUS OPERABLE AS A PUMP OR A MOTOR AND HAVING ACASING, A ROTARY CYLINDER BARREL IN SAID CASING, AND AXIALLY DIRECTEDFACE OF SAID BARREL HAVING LIQUID-TRANSFER PORTS, A NON-ROTATING FACEVALVE OPPOSED AXIALLY AGAINST SAID BARREL FACE, SAID CASING AND SAIDVALVE EACH HAVING THERETHROUGH TWO PASSAGEWAYS ARRANGED SYMMETRICALLY ONOPPOSITE SIDES OF THE ROTARY AXIS OF SAID BARREL AND IN OPERATIVECOMMUNICATION WITH SAID PORTS, THE IMPROVEMENT COMPRISING MUTUALLYOPPOSED ENDS OF SAID PASSAGEWAYS IN SAID CASING AND SAID VALVE BEING OFTHE SAME ARCUATE CROSS-SECTIONAL SHAPE SUBTENDING AN ANGLE OF NEARLY180* TO SAID AXIS AND SAID PASSAGEWAYS IN SAID VALVE EACH HAVING A WALLSURFACE DIRECTED SUBSTANTIALLY AXIALLY AWAY FROM SAID BARREL FACE ANDBEING OF ARCUATE SHAPE SUBTENDING AN ANGLE OF NEARLY 180* TO SAID AXIS.